1. Field of the Invention
The present invention relates to an image forming apparatus and image forming method, and a storage medium thereof.
2. Description of the Related Art
In recent years, there has been a need for reduction in a toner bearing amount in order to save energy in an image forming apparatus which employs an electrophotographic method. In order to reduce a toner bearing amount, a method to reduce exposure intensity of a laser light emitted by an exposure apparatus, a method to perform line screen processing on an image (U.S. Pat. No. 8,326,165), etc. are known. Tone reproduction in a case when line screen processing is performed on the high density portion will be described using conceptual diagrams of FIG. 17A and FIG. 17B.
FIG. 17A and FIG. 17B are diagrams for explaining the line screen processing. FIG. 17A shows a normal screen pattern in which line screen processing is not performed on the high density portion, and FIG. 17B shows a screen pattern in which line screen processing is also performed on the high density portion.
In the meanwhile, when exposure intensity is reduced, an exposure amount is reduced, and hence toner is not deposited on a low-density image, which causes a problem that the low-density image cannot be formed stably. Further, when the line screen processing is performed on image data, the exposure intensity is not reduced; however, there was a problem that an exposed region and a non-exposed region are undesirably formed in a stripe manner, that is, density variability is occurred in a high-density image.